Cisco 813 Especificações descarregar pdf (Página 38)

CHAPTER 3

Spanning Tree

Portfast

Portfast is a Cisco-proprietary enhancement to Spanning Tree that helps speed up network convergence. It is for access

(user) ports only. Portfast causes the port to transition directly to forwarding, bypassing the other STP states. Connecting

a switch to a Portfast port can cause loops to develop. Configure Portfast on an interface or interface range:

(config-if)# spanning-tree portfast

It can also be configured globally:

(config)#

spanning-tree portfast default

Rapid Spanning Tree

Rapid Spanning Tree (RSTP) 802.1w is a standards-based, nonproprietary way of speeding STP convergence. Switch

ports exchange an explicit handshake when they transition to forwarding. RSTP describes different port states than

regular STP, as shown in Table 3-3.

Table 3-3 Comparing 802.1d and 802.1w Port States

STP Port State Equivalent RSTP Port State

Disabled Discarding

Blocking Discarding

Listening Discarding

Learning Learning

Forwarding Forwarding

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CCNP SWITCH 642-813 Quick Reference by Denise Donohue

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Cisco 813 Especificações Página 38